In the past many arrangements have been proposed to control the flow of inlet gases into, and exhaust gases from, the combustion chamber of an internal combustion engine. The conventional arrangement has a pair of reciprocating poppet valves in the head of the combustion chamber, one valve controlling the flow of gases from the inlet tract into the combustion chamber, and the other valve controlling the flow of exhaust gases from the combustion chamber to the exhaust tract after combustion. Such arrangements have limitations in that the valve diameter and therefore the area available for flow of the gases is restricted due to the necessity to fit at least two valves into the head of the combustion chamber, and this restriction limits the amount of inlet gases that can be induced into the engine and therefore restricts the power of the engine.
It is a further feature of existing valve mechanisms for internal combustion engines, that the flow of inlet gases is completely stopped once in every cycle requiring the gases to be quickly accelerated once the inlet valve has opened. The inertia of the gas also restricts the amount of gas that can be induced into the combustion chamber during the inlet phase of the operating cycle.